Yamaha 60 HP Two Stroke Overheat Frustrations

[ausnoelm]

Super caliber, some tips on w/p replacement. Take the driveshaft key and grind down one flat side. Install with grease. Use a small screwdriver and put grease in the four water pump bolt threads on top of lwr unit.. Do not use any Sealants. Use fresh grease on driveshaft splines,, but not on the top of shaft.. Pull up and slowly turn driveshaft clock wise, while tapping down impeller and keepers.. This preload the gears and stops clunking.. Best with two people..don't watch YouTube outboard repair videos..ain't seen one done right yet... There are a lot of tricks to do the job correctly.......after just rereading complete post,, I noticed you replaced w.p housing. On a complete new kit or new housing they dont give you the last (top) grommlet.. Its round with two sideways locking tabs. I've seen 100's of them missing..font know why yammy does that,, but you have yo salvage the old one out other top of your old pimp housing

Why would you grind down the key? It's made to fit as it is, grinding it down is a futile thing to do.

[Supercaiber]

Well, unfortunately I’m still having the same issue.

New pump kit installed with new housing, seals and loctite as recommended. I also replaced the thermostat just for kicks.

So do I pull the head, or live with it and limit the idling?

[Keithbaja]

U grind the keyway because yammys are nightmares.. Way TOO tight.. Super caliber ,, how are you testing engine temp ?? Has this motor had a impeller with broken vanes in the past ?? Cooling systems are very simple, but very often not done correctly.. Where da hell are you.. LOL... Damn,, been so long,, I forgot your main complaint ?? Idle/low speed over heat if I remember. U can also remove gearcase and run a garden hose up to the water pick up tube and use a garden house with house water pressure.....Keith & the famous Tasha dog

[Supercaiber]

U grind the keyway because yammys are nightmares.. Way TOO tight.. Super caliber ,, how are you testing engine temp ?? Has this motor had a impeller with broken vanes in the past ?? Cooling systems are very simple, but very often not done correctly.. Where da hell are you.. LOL... Damn,, been so long,, I forgot your main complaint ?? Idle/low speed over heat if I remember. U can also remove gearcase and run a garden hose up to the water pick up tube and use a garden house with house water pressure.....Keith & the famous Tasha dog

Hey Keith,

I’m testing the engine temp with an IR gun on the cylinder head. Top two cylinders hit about 200 when alarm goes off. Bottom cylinder is around 185 when the alarm goes.

I’ve also changed the temp sending unit and still get low rpm overheat in about 5-6 minutes from a cold start.

As far as a broken vane in the past, I’m not sure. The one I first replaced was at 50 hours right when I bought the boat and they were all there.

I live in Houston,Tx if by chance you’re local

[zenoahphobic]

Looks like the pump wasn’t the problem.
And if you changed the impeller 50hrs ago, and the one on it has no vanes missing, then unlikely that is causing a blockage. But don’t completely dismiss this.
You need to explore further. And I would attempt to remove the head water cover and inspect cooling passages.
I used “attempt” to do this gently and be prepared to break bolts, have subsequent repair ready: removal of broken thread and new helicoil threads ready.

[Keithbaja]

Being I've lived in mexico a good part of my life,,, I've been called Local many times. I live in the Monterrey bay area, Ca.. Nice place. I seek out difficult problem units like this and always find and fix the unit.. But,, alas, your a long ways away.. U might consider the garden hose trick if you have good house pressure. #40 psi and up.. That Eliminates the complete lwr half of the the outboard. Just make sure u us a wire coat hanger to run up and ck/clear pwr head water intake tube....do the the therms ur using have the little air bleed crinkles/Vee's in them ??

[zenoahphobic]

I’m also wrestling with your statement that the pee water immediately goes boiling hot after the alarm goes off.
There is no physical connection with the alarm and control of the cooling water flow. The alarm simply goes off when the temperature of the sender is reached.
So, be very sure of this, as it does indicate a piece of something shifts to block(this was already suggested above).
Either way, surgery probably necessary. Pulling the head will give you access down the sides of the cylinders and a chance to reverse hose water down them. I ‘ll do head jacket first though.

Make sure you catch any flushing water to find any rubbish, otherwise you will never be sure you found the problem or not!

[99yam40]

On my brothers C60 I dropped the lower unit and hooked up a hose to the pipe heading up to powerhead.
hooked up to a water hose and air hose also.
pulled the stat and housing off and turned on the water.
shot some comressed air into the water from time to time to move things around in the block.
water flowed out the stat cover hole and the normal prop hub .
we did get debris out both places.( scale, shell, or sand etc.)

I thought he figured it out when he said he did not have #1 and #4 in the pump housing, letting too much water not to get up to the power heard to fill it up during idle rpm so the top cylinders run too hot

[Supercaiber]

Okay, so I’ve isolated the issue to the lower unit. Today I ran it with my hose connected straight to the water pickup tube without the lower unit. I kept the water pressure low to ensure it matched low rpm’s and all three cylinders held between 144-149 degrees.

I did order the seals I thought were missing from the water pump but can’t determine where they go? It looks like they may be installed at the top of my water pickup already going into the power head.

next steps? Yami dealer? Or anyone want to make a few bucks with a video call?

[Supercaiber]

Here’s a few pictures from today along with the two seals

[panasonic]

See my post #25 of this thread with the link I included. Items # 1, 4, and 16 are the parts you need. You have all those? The diagram shows you how they go. I will look and see if I got the service manual instructions and get back to you in a bit.

Getting my own boat uncovered from the winter right now..

[Keithbaja]

Part # 1 goes on the outside top discharge hole port. As in the the water tube coming down from pwr head would enter this seal first. If not installed will overheat at low rpms.. This is a common mistake I sea with yammys all the time. F- ing install it and let's call this a done deal..Very Simple... GRrrr..

[Supercaiber]

Okay, I get it…but there’s no way to attach it to the water pump housing. Does it slide onto the pickup tube and rest flush on the housing once the lower unit is installed?

[zenoahphobic]

Okay, I get it…but there’s no way to attach it to the water pump housing. Does it slide onto the pickup tube and rest flush on the housing once the lower unit is installed?

Methinks that’s right. There should be a ridge on that tube that compresses it to the other top seal when in place (you can’t see this when together).
Perhaps the non inclusion of this ring is because it technically is not a seal and not part of the water pump (belongs to the pipe).
Ofcourse one needs to check whether this ring is necessary and works. Gluing the top inserted seal will ensure it stays there under pressure. It wobbling out presumably causes enough leakage causing loss of pressure.

[Keithbaja]

# 1 installs in the very top of water pump housing. Pushing it downward motion
in the hole
When installing gearcase the copper tube from pwr head will slide down into it and complete the seal